🚀 go-pugleaf

seifert@netcom.com (Rich Seifert) writes:

>In article <1992Sep24.204418.936@mdd.comm.mot.com>, pchan@mdd.comm.mot.com (Pat Chan) writes:
>> I've two Ethernet LAN's (10Mbps) connected together through 
>> bridges and dedicated T1 (~1.5Mbps), as follows:
>> 
>>        LAN A           T1          LAN B
>>     --------- Bridge ------ Bridge------------
>> 
>> I've a file in LAN A. Say an application (in LAN A) requires 
>> w seconds to retrieve this file. 
>> Does it mean that an application requires w*10/1.5 seconds 
>> to retrieve the file from LAN B????

>This is a wonderful question!! It forces us to look at what is 
>really going on.

>In the initial case (file transfer on a single LAN segment), the
>length of time to transfer the file is a function of:
>   -The performance of the application responsible for the file transfer
>    (e.g., the FTP implementation)
>   -The transfer rates of the disks themselves on the two machines
>   -The protocol overhead in the two stations (IP, other NOS services)
>   -The device drivers for the NIC cards
>   -The NIC cards themselves
>   -and finally the tranfer rate of the Ethernet.

....  much good stuff deleted

One more factor to add to your list: compression in the Ethernet to T1
bridges. We run several such links between the Universities on BCnet using
Vitalink bridges to go from Ethernet to T1 and back, and as I recall the 
Vitalinks use a proprietary protocol on the T1 side that does some kind of 
data compression to boost the throughput between the two ethernets to more
than what a staight translation of bits to T1 would imply.

>-- 
>Rich Seifert                    Networks and Communications Consulting
>seifert@netcom.com              (408) 996-0922
>                                (408) 996-2860 FAX
>"... specialists in Local Area Networks and Data Communications systems"

Peter Van Epp / Operations and Technical Support 
Simon Fraser University, Burnaby, B.C. Canada